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　　(Science,October 29,2024)-Scientists have discovered a gene variant that could make some parents more likely to have girls than boys.

　　科学家们发现了一种基因变异，可能会使一些父母更有可能生女孩而不是男孩。

　　In the new study, researchers analyzed the genomes of around 450,000 males and females in the U.K. who contributed genetic and health data to the U.K. Biobank — a large, publicly available database.

　　在新研究中，研究人员分析了英国约45万名男性和女性的基因组，这些人为英国生物样本库（U.K. Biobank）——一个大型公开数据库——贡献了遗传和健康数据。

　　The scientists found that one particular version of a gene — named rs144724107 — boosted a person's likelihood of having a daughter by 10%. That means, in a given pregnancy, a person with this variant has a 60% chance of having a daughter rather than the expected 50% chance. It's unclear whether the rs144724107 variant needs to be carried by mom, dad or both to influence this offspring-sex ratio.

　　科学家们发现，一种名为rs144724107的特定基因版本使一个人生女儿的可能性增加了10%。这意味着，在特定怀孕中，拥有这种变异的人有60%的机会生女儿，而不是预期的50%。目前尚不清楚rs144724107变异是否需要由母亲、父亲或双方携带才能影响后代的性别比例。

　　It's also not yet known exactly how this gene variant raises the chances that someone has female offspring. But researchers do know that, within DNA molecules, rs144724107 is located near a member of a gene family called ADAMTS. This family has been linked to both sperm production and fertilization, the process by which sperm and eggs fuse to form embryos. Given this proximity, rs144724107 could exert its effects on sex by affecting how this gene gets switched on and off, the researchers told Live Science.

　　目前尚不清楚这种基因变异如何具体提高某人拥有女性后代的几率。但研究人员确实知道，在DNA分子中，rs144724107位于一个名为ADAMTS的基因家族成员附近。这个家族与精子生成和受精过程有关，受精是精子和卵子融合形成胚胎的过程。研究人员告诉《生活科学》，鉴于这种接近性，rs144724107可能通过影响该基因的开关来影响性别。

　　The findings, published Oct. 16 in the journal Proceedings of the Royal Society B: Biological Sciences, may bolster the idea that a classic evolutionary biology theory applies to people.

　　这些发现于10月16日发表在《皇家学会B辑：生物科学》期刊上，可能加强了经典进化生物学理论适用于人类的想法。

　　The theory, known as Fisher's principle, suggests that, most of the time, sexually reproducing organisms produce equal numbers of male and female offspring.

　　这一理论，被称为费希尔原理，表明大多数情况下，有性生殖的生物会产生数量相等的雄性和雌性后代。

　　The theory goes that if a population has more males than females, evolutionary pressures would favor gene variants that boost the number of females, thus balancing the ratio, said study co-author Jianzhi Zhang, a professor of ecology and evolutionary biology at the University of Michigan. The same thing would also happen the other way around, if there are more females than males.

　　研究合著者、密歇根大学生态与进化生物学教授张建志表示，理论认为，如果一个种群中雄性多于雌性，进化压力将倾向于有利于增加雌性数量的基因变异，从而平衡性别比例。同样的情况也会反过来发生，如果雌性多于雄性。

　　To prove this theory, researchers need to identify gene variants that influence the number of male and female offspring that an individual has. In humans, such variants have been difficult to detect, in part because people generally bear relatively few offspring, Zhang said.

　　为了证明这一理论，研究人员需要识别影响个体所生男性后代和女性后代数量的基因变异。张说，在人类中，这类变异很难被检测到，部分原因是人们通常生育的后代数量相对较少。

　　However, the enormous U.K. Biobank dataset enabled the team to detect the rs144724107 variant, Zhang said. The database doesn't record the sex of its participants' offspring, but it does include information on the sex of participants' siblings. So instead of linking the gene variant in a parent to the sex of their offspring, the team worked in reverse, checking the sex of the siblings and then tracing this back to the gene variants carried by their parents.

　　然而，张说，庞大的英国生物银行数据集使团队能够检测到rs144724107变体。该数据库不记录参与者后代的性别，但确实包含参与者兄弟姐妹的性别信息。因此，团队没有将父母的基因变体与后代的性别联系起来，而是反向工作，检查兄弟姐妹的性别，然后追溯到父母携带的基因变体。

　　The researchers found that only 0.5% of the participants carried rs144724107. But they suspect there are other variants that similarly influence offspring sex. Some people might happen to have variants that increase the sex ratio in favor of males or females, while others' genes will decrease the sex ratio, Zhang said.

　　研究人员发现，只有0.5%的参与者携带rs144724107。但他们怀疑还有其他变体同样影响后代的性别。张说，有些人可能碰巧有增加性别比例偏向男性或女性的变体，而其他人的基因则会降低性别比例。

　　But overall, at the population level, the sex ratio is about 0.5, he said.

　　但总体而言，在人口层面上，性别比例约为0.5，他说。

　　 The team's findings will need to be confirmed in other groups of people. In a separate analysis in the same study, the team couldn't find the rs144724107 variant in the genomes of 14,500 postmenopausal women in the U.S. from the Women's Health Initiative (WHI). Unlike the U.K. Biobank, the WHI includes data on the sex of participants' offspring.

　　该团队的发现需要在其他人群中得到确认。在同一研究中的另一项分析中，该团队在美国妇女健康倡议（WHI）的14,500名绝经后妇女的基因组中未能找到rs144724107变异。与英国生物银行不同，WHI包括了参与者后代性别的数据。

　　The team will also need to see if similar variants exist in the genomes of more diverse populations. The scientists exclusively included people of European ancestry in this study.

　　团队还需要查看更多样化人群的基因组中是否存在类似的变异。科学家们在这项研究中只包括了欧洲血统的人。